William bypassed Beckham's agent and wrote directly to the soccer star asking him to appear at the event next month, The (London) Mirror reported Friday.
William and Prince Harry are both fans of the former England captain, the newspaper said. Beckham immediately accepted the invitation and plans call for him to introduce one of the acts at the July 1 concert -- possibly Elton John or Take That, The Mirror said.
The princes have said they are staging the concert as a counter measure to media attention on the sensational aspects of their mother's life and death.
"It would be one of those things she would adore because the whole point is, this is for her -- it's not for any other reason," William told the BBC. "We want people to remember all those good things she did. After 10 years there have been a rumbling of people bringing up the bad."
The talent lineup for the concert includes Duran Duran, Joss Stone and Bryan Ferry.